Composite article with coolant channels and tool fabrication method

ABSTRACT

Embodiments of the present invention include composite articles comprising at least a first region and a second region and methods of making such articles. The first region may comprise a first composite material, wherein the first region comprises less than 5 wt. % cubic carbides by weight, and the second region may comprise a second composite material, wherein the second composite material differs from the first composite material in at least one characteristic. The composite article may additionally comprise at least one coolant channel. In certain embodiments, the first and second composite material may individually comprise hard particles in a binder, wherein the hard particles independently comprise at least one of a carbide, a nitride, a boride, a silicide, an oxide, and solid solutions thereof and the binder comprises at least one metal selected from cobalt, nickel, iron and alloys thereof. In specific embodiments, the first composite material and the second composite material may individually comprise metal carbides in a binder, such as a cemented carbide.

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

The present invention is generally directed to methods of formingarticles, such as tool blanks, having a composite construction includingregions of differing composition and/or microstucture. The presentinvention is additionally directed to rotary tools and tool blanks forrotary tools having a composite construction and at least one coolantchannel. The method of the present invention finds general applicationin the production of rotary tools and may be applied in, for example,the production of cemented carbide rotary tools used in material removaloperations such as drilling, reaming, countersinking, counterboring, andend milling.

DESCRIPTION OF THE INVENTION BACKGROUND

Cemented carbide rotary tools (i.e., tools driven to rotate) arecommonly employed in machining operations such as, for example,drilling, reaming, countersinking, counterboring, end milling, andtapping. Such tools are typically of a solid monolithic construction.The manufacturing process for such tools may involve consolidatingmetallurgical powder (comprised of particulate ceramic and binder metal)to form a compact. The compact is then sintered to form a cylindricaltool blank having a solid monolithic construction. As used herein,monolithic construction means that the tools are composed of a material,such as, for example, a cemented carbide material, having substantiallythe same characteristics at any working volume within the tool.Subsequent to sintering, the tool blank is appropriately machined toform the cutting edge and other features of the particular geometry ofthe rotary tool. Rotary tools include, for example, drills, end mills,reamers, and taps.

Rotary tools composed of cemented carbides are adapted to manyindustrial applications, including the cutting and shaping of materialsof construction such as metals, wood, and plastics. Cemented carbidetools are industrially important because of the combination of tensilestrength, wear resistance, and toughness that is characteristic of thesematerials. Cemented carbides materials comprise at least two phases: atleast one hard ceramic component and a softer matrix of metallic binder.The hard ceramic component may be, for example, carbides of elementswithin groups IVB through VIB of the periodic table. A common example istungsten carbide. The binder may be a metal or metal alloy, typicallycobalt, nickel, iron or alloys of these metals. The binder “cements” theceramic component within a matrix interconnected in three dimensions.Cemented carbides may be fabricated by consolidating a metallurgicalpowder blend of at least one powdered ceramic component and at least onepowdered binder.

The physical and chemical properties of cemented carbide materialsdepend in part on the individual components of the metallurgical powdersused to produce the material. The properties of the cemented carbidematerials are determined by, for example, the chemical composition ofthe ceramic component, the particle size of the ceramic component, thechemical composition of the binder, and the ratio of binder to ceramiccomponent. By varying the components of the metallurgical powder, rotarytools such as drills and end mills can be produced with uniqueproperties matched to specific applications.

Monolithic rotary tools may additionally comprise coolant channelsextending through its body and shank to permit the flow of a coolant,such as oil or water, to the cutting surfaces of the rotary tool. Thecoolant may enter the channel at the shank end and exit at the drillpoint. The coolant cools the rotary tool and work piece and assists inejecting chips and dirt from the hole. The use of coolant duringmachining operations allows for the use of higher cutting speeds of therotary tool and faster feed rates, in addition to extending tool life.Rotary tools with coolant channels are especially suited for drillingdeep holes in hard materials.

However, the monolithic construction of rotary tools inherently limitstheir performance and range of applications. As an example, FIG. 1depicts side and end views of a twist drill 10 having a typical designused for creating and finishing holes in construction materials such aswood, metals, and plastics. The twist drill 10 includes a chisel edge11, which makes the initial cut into the workpiece. The cutting tip 14of the drill 10 follows the chisel edge 11 and removes most of thematerial as the hole is being drilled. The outer periphery 16 of thecutting tip 14 finishes the hole. During the cutting process, cuttingspeeds vary significantly from the center of the drill to the drill'souter periphery. This phenomenon is shown in FIG. 2, which graphicallycompares cutting speeds at an inner (D1), outer (D3), and intermediate(D2) diameter on the cutting tip of a typical twist drill. In FIG. 2(b),the outer diameter (D3) is 1.00 inch and diameters D1 and D2 are 0.25and 0.50 inch, respectively. FIG. 2(a) shows the cutting speeds at thethree different diameters when the twist drill operates at 200revolutions per minute. As illustrated in FIGS. 2(a) and (b), thecutting speeds measured at various points on the cutting edges of rotarytools will increase with the distance from the axis of rotation of thetools.

Because of these variations in cutting speed, drills and other rotarytools having a monolithic construction will not experience uniform wearand/or chipping and cracking of the tool's cutting edges at differentpoints ranging from the center to the outside edge of the tool's cuttingsurface. Also, in drilling casehardened materials, the chisel edge istypically used to penetrate the case, while the remainder of the drillbody removes material from the casehardened material's softer core.Therefore, the chisel edge of conventional drills of monolithicconstruction used in that application will wear at a much faster ratethan the remainder of the cutting edge, resulting in a relatively shortservice life for such drills. In both instances, because of themonolithic construction of conventional cemented carbide drills,frequent regrinding of the cutting edge is necessary, thus placing asignificant limitation on the service life of the bit. Frequentregrinding and tool changes also result in excessive downtime for themachine tool that is being used.

Therefore, composite articles, such as composite rotary tools have beenused, such as those tools described in described in U.S. Pat. No.6,511,265 which is hereby incorporated by reference in its entirety. Ifdesigned properly, composite rotary tools may have increased toolservice life as compared to rotary tools having a more monolithicconstruction. However, there exists a need for drills and other rotarytools that have different characteristics at different regions of thetool and comprise coolant channels. As an example, a need exists forcemented carbide drills and other rotary tools that will experiencesubstantially even wear regardless of the position on the tool facerelative to the axis of rotation of the tool and allow cooling at thecutting surfaces. There is a need for a composite rotary tool havingcoolant channels so composite rotary tools may have the same benefits asmonolithic rotary tools. There is also a need for a versatile method ofproducing composite rotary tools and composite rotary tools comprisingcoolant channels.

SUMMARY

Embodiments of the present invention include composite articlescomprising at least a first region and a second region. The first regionmay comprise a first composite material, wherein the first regioncomprises less than 5 wt. % cubic carbides by weight, and the secondregion may comprise a second composite material, wherein the secondcomposite material differs from the first composite material in at leastone characteristic. The composite article may additionally comprise atleast one coolant channel. In certain embodiments, the first and secondcomposite material may individually comprise hard particles in a binder,wherein the hard particles independently comprise at least one of acarbide, a nitride, a boride, a silicide, an oxide, and solid solutionsthereof and the binder comprises at least one metal selected fromcobalt, nickel, iron and alloys thereof. In specific embodiments, thefirst composite material and the second composite material mayindividually comprise metal carbides in a binder.

The characteristic may be at least one characteristic selected from thegroup consisting of modulus of elasticity, hardness, wear resistance,fracture toughness, tensile strength, corrosion resistance, coefficientof thermal expansion, and coefficient of thermal conductivity. Thecomposite article may be one of rotary tool, a rotary tool blank, adrill, an end mill, a tap, a rod, and a bar, for example. In someembodiments, the composite article may further comprises two or morecoolant channels and the coolant channels may be substantially straightor substantially helical shape.

Embodiments of the present invention further include a method of formingan article, comprising coextruding at least two composite materialscomprising metal carbides to form a green compact. The compositematerials may be as described above. The coextruding at least twocomposite materials may be performed through a die and, in certainembodiments, the die may comprise means for making internal channels inthe green compact. The die may comprise at least one wire to form aninternal channel within the green compact, wherein the wire may be rigidor flexible.

Embodiments also include a method of producing a rotary tool having acomposite structure comprising placing an extruded first powder metalinto a first region of a void of a mold, placing a second metallurgicalpowder metal into a second region of the void, the extruded first powdermetal differing from the second metallurgical powder, and compressingthe mold to consolidate the extruded first powder metal and the secondpowder metal to form a green compact. The green compact may be sinteredto form the article. Material may be removed material from the greencompact to provide at least one cutting edge prior to or aftersintering.

The reader will appreciate the foregoing details and advantages of thepresent invention, as well as others, upon consideration of thefollowing detailed description of embodiments of the invention. Thereader also may comprehend such additional details and advantages of thepresent invention upon using the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present invention may be betterunderstood by reference to the accompanying drawings in which:

FIGS. 1(a) and 1(b) are plan and on-end views, respectively, of aconventional twist drill with coolant channels;

FIG. 2(a) is a graph indicating cutting speeds at the three diametersD1, D2, and D3 of a conventional twist drill indicated in FIG. 2(b);

FIGS. 3(a) and (b) include a transverse section (FIG. 3(a) and alongitudinal section (FIG. 3(b)) of rods produced by embodiments of themethod of the present invention comprising a core of centered carbidegrade B and a shell of cemented carbide grade A;

FIGS. 4(a)-(d) are representations of a cross-sectional views of anembodiments of a composite cemented carbide;

FIGS. 5 (a)-(d) are embodiments of blanks showing examples of thedifferent configurations of coolant channels, such as a straight singlecoolant channel (FIG. 5(a)); two straight channels (FIG. 5(b)); twohelical or spiral channels (FIG. 5(c)); and three helical or spiralchannels (FIG. 5(d));

FIG. 6(a) is a representation of the coextrusion pressing apparatus usedin coextrusion of a tube of grade A and a rod of grade B through a diewith internal spiral serrations to produce a blank with helical orspiral channels.

FIG. 6(b) is a representation of a channel die;

FIG. 6(c) is a photograph of a coextruded composite cemented carbide rodwith internal channels exiting from a die with spiral serrations;

FIG. 7 is representation of a dry bag isostatic pressing apparatus usedin an embodiment of a method of the present invention includingconsolidating cemented carbide grade B with an extruded rod withinternal channels made from a cemented carbide grade A;

FIG. 8(a) is a photograph of a longitudinal cross-section of a compositerod with internal coolant channels of the present invention, the nylonwires in the photograph have been inserted in the channels to moreclearly show their location and the path of the coolant channels; and

FIG. 8(b) is a photograph of a longitudinal cross-section of a drillmade from a composite cemented carbide having internal coolant channels.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention provides rotary cutting tools, cutting toolblanks, rods, and other articles having a composite construction and amethod of making such articles. The articles may further compriseinternal channels, such as coolant channels, if desired. As used herein,a rotary tool is a tool having at least one cutting edge that is drivento rotate. As used herein, “composite” construction refers to an articlehaving regions differing in chemical composition and/or microstructure.These differences result in the regions having properties differing withrespect to at least one characteristic. The characteristic may be atleast one of, for example, hardness, tensile strength, wear resistance,fracture toughness, modulus of elasticity, corrosion resistance,coefficient of thermal expansion, and coefficient of thermalconductivity. Composite rotary tools that may be constructed as providedin the present invention include drills and end mills, as well as othertools that may be used in, for example, drilling, reaming,countersinking, counterboring, end milling, and tapping of materials.

The present invention more specifically provides a composite rotary toolhaving at least one cutting edge, at least two regions of cementedcarbide material that differ with respect to at least onecharacteristic, and at least one coolant channel. The differingcharacteristics may be provided by variation of at least one of thechemical composition and the microstructure among the two regions ofcemented carbide material. The chemical composition of a region is afunction of, for example, the chemical composition of the ceramiccomponent and/or binder of the region and the carbide-to-binder ratio ofthe region. For example, one of the two cemented carbide materialregions of the rotary tool may exhibit greater wear resistance, enhancedhardness, and/or a greater modulus of elasticity than the other of thetwo regions.

Aspects of present invention may be described in relation to the toolblank 400, shown in FIG. 4(a) in a cross-sectional view transverse tothe axis. The tool blank 400 is a generally cylindrical sintered compactwith two coaxially disposed cemented carbide regions 410, 420 andcoolant channels 430. It will be apparent to one skilled in the art,however, that the following discussion of the present invention also maybe adapted to the fabrication of composite rotary tools and tool blankshaving more complex geometry and/or more than two regions. Thus, thefollowing discussion is not intended to restrict the invention, butmerely to illustrate embodiments of it.

In the embodiment of FIG. 4(a), the cylindrical rotary tool blank 400 iscomprised of two differing cemented carbide regions, a core region 400and an outer region 410. The core region 420 and the outer region 410are both of a cemented carbide material including ceramic particles in acontinuous matrix of binder. Preferably, the cemented carbide materialsin the core region 420 and in the outer region 410 include a ceramiccomponent composed of carbides of one or more elements belonging togroups IVB through VIB of the periodic table including less than 5%cubic carbides or, in some applications, less than 3 wt. % cubiccarbides. Embodiments of the present invention may comprise less than 5wt. % cubic carbides because cubic carbides may reduce strengthtransverse rupture strength of the article, increase the productioncosts, and reduce the fracture toughness. This is especially importantfor tools used to machine hard work pieces where the machining resultsin a shearing action and the strength of the drill should be thegreatest.

The ceramic component preferably comprises about 60 to about 98 weightpercent of the total weight of the cemented carbide material in eachregion. The carbide particles are embedded within a matrix of bindermaterial that preferably constitutes about 2 to about 40 weight percentof the total material in each region. The binder preferably is one ormore of Co, Ni, Fe, and alloys of these elements. The binder also maycontain, for example, elements such as W, Cr, Ti, Ta, V, Mo, Nb, Zr, Hf,and C up to the solubility limits of these elements in the binder.Additionally, the binder may contain up to 5 weight percent of elementssuch as Cu, Mn, Ag, Al, and Ru. One skilled in the art will recognizethat any or all of the constituents of the cemented carbide material maybe introduced in elemental form, as compounds, and/or as master alloys.

The core region 420 of the tool blank 400 is autogenously bonded to theouter region 410 at an interface 415. The interface 440 is shown in FIG.4(a) to be cylindrical, but it will be understood that the shapes of theinterfaces of cemented carbide material regions of the composite rotarytools of the present invention are not limited to cylindricalconfigurations. The autogenous bond between the regions at the interface415 may be formed by, for example, a matrix of binder that extends inthree dimensions from the core region 420 to the outer region 410, orvice versa. The ratio of binder to ceramic component in the two regionsmay be the same or different and may be varied between the regions toaffect the regions' relative characteristics. By way of example only,the ratio of binder to ceramic component in the adjacent regions of thecomposite tool blank 30 may differ by 1 to 10 weight percent. Thecharacteristics of the cemented carbide materials in the differentregions of the composite rotary tools of the present invention may betailored to particular applications.

One skilled in the art, after having considered the description ofpresent invention, will understand that the improved rotary tool of thisinvention could be constructed with several layers of different cementedcarbide materials to produce a progression of the magnitude of one ormore characteristics from a central region of the tool to its periphery.Thus, for example, a twist drill may be provided with multiple,coaxially disposed regions of cemented carbide material and wherein eachsuch region has successively greater hardness and/or wear resistancethan the adjacent, more centrally disposed region. Coolant channels maybe provided in any of the regions or intersecting two or more regions.The method of the present invention provides great design flexibility inthe design of extruded articles. Alternately, rotary tools of thepresent invention could be made with other composite configurationswherein differences in a particular characteristic occur at differentregions of the tool.

A major advantage of the composite cemented carbide rotary tools of thepresent invention is the flexibility available to the tool designer totailor properties of regions of the tools to suit differentapplications. For example, the size, location, thickness, geometry,and/or physical properties of the individual cemented carbide materialregions of a particular composite blank of the present invention may beselected to suit the specific application of the rotary tool fabricatedfrom the blank. In addition, the coolant channels may be located in thedesired locations and be helical, spiral, linear, or a combination ofsuch shapes. Thus, for example, the stiffness of one or more cementedcarbide regions of the rotary tool experiencing significant bendingduring use may be of a cemented carbide material having an enhancedmodulus of elasticity; the hardness and/or wear resistance of one ormore cemented carbide regions having cutting surfaces and thatexperience cutting speeds greater than other regions may be increased;and/or the corrosion resistance of regions of cemented carbide materialsubject to chemical contact during use may be enhanced.

FIGS. 4(b) and 4(c) show additional embodiments of the presentinvention. These embodiments may additional comprise channels, such ascoolant channels. The embodiment of FIG. 4(b) comprises a tube withinternal regions of different cemented carbide grades. In this example,the rod 440 comprises an outer region 441 of a first cemented carbide, afirst inner region 442 of a second cemented carbide, and an additionalinner regions 443 that could comprise the same or different cementedcarbides. The rod 440 could be produced, for example, by coextuding aset 450 comprising a tube 451 filled with rods 452 and 453. Rods 452 maybe formed from a cemented carbide that has at least one characteristicthat differs from the rods 453, for example.

By way of example only, additional embodiments of rotary tools of thepresent invention are shown in FIGS. 4 and 5. FIG. 4 depicts a stepdrill 110 constructed according to the present invention. The drill 110includes a cutting portion 112 including several helically orientedcutting edges 114. The drill 110 also includes a mounting portion 116that is received by a chuck to mount the drill to a machine tool (notshown). The drill 110 is shown in partial cross-section to reveal threeregions of cemented carbide materials that differ relative to oneanother with regard to at least one characteristic. A first region 118is disposed at the cutting tip of the drill 110. The cemented carbidematerial from which region 118 is composed exhibits an enhanced wearresistance and hardness relative to a central region 120 forming thecore of the drill 110. The core region is of a cemented carbide materialthat exhibits an enhanced modulus of elasticity relative to theremaining two regions. The enhanced modulus of elasticity reduces thetendency of the drill 110 to bend as it is forced into contact with awork piece. The drill also includes an outer region 122 that defines theseveral helically oriented cutting edges 114. The outer region surroundsand is coaxially disposed relative to the core region 120. The outerregion 122 is composed of a cemented carbide material that exhibitsenhanced hardness and wear resistance relative to both the core region120 and the tip region 118. The cutting surfaces 114 that are defined bythe outer region 122 experience faster cutting speeds than cuttingregions proximate to the drill's central axis. Thus, the enhanced wearresistance and hardness of the outer region 122 may be selected so thatuniformity of wear of the cutting surfaces is achieved.

Embodiments of the present invention also include additional methods ofmaking composite cemented carbide articles. Embodiments include a methodof forming a composite article by coextruding at least two compositematerials comprising cemented carbides to form a green compact. Thecoextruding may be performed by direct or indirect extrusion process.The feed chamber of the extruder is filled with two grades of materials,such as two grades of carbide powder and binder powder mixed with aplastic binder. The plastic binder material may be present inconcentrations from about 33 wt. % to 67 wt. % and decreases theviscosity of the powder metal mixture to allow extrusion.

The extrusion process for cemented carbides is well known in the art. Ina typical extrusion process, metal powders are mixed with a plasticbinder. Any typical plastic binder may be used such as plastic bindersbased upon benzyl alcohol, cellulose, polymers, or petroleum products.Typically, a high sheen mixing process is used to ensure intimatecontact between the metal powders and the plastic binder.

The metal/binder mixer may then be pumped by screw feeder through theextruder to produce an extruded product. Embodiments of the method ofthe present invention include coextrusion of at least two cementedcarbide grades. The term coextrusion, as used herein, means that twomaterials are extruded simultaneously to form a single articleincorporating both materials. Any coextrusion process may be used in themethod of the present invention such as, pumping two grades of cementedcarbide to separate sections of funnel or die wherein the two gradesexit the die in intimate contact with each other.

An embodiment of the coextrusion process is shown in FIG. 6(a). The feedchamber 600 is filled with a rod 610 of a first grade of cementedcarbide powder and a tube 620 of a second grade of cemented carbidepowder. The rod 610 and the tube 620 were individually formed byseparate extrusion processes as known in art. In certain embodiments,the tube 620 may be extruded directly into the feed chamber 600. The rod610, formed in a separate extrusion process may then be inserted intothe tube 620 already in the feed chamber 600.

In this embodiment of the extrusion process, a plunger (not shown)pushes the rod 610 and the tube 620 through the feed chamber and intothe funnel 630. The funnel 630 reduces in cross-sectional area from thefeed chamber to the die 640. The funnel 630 causes compaction andconsolidation of the cemented carbide powders resulting in intimatecontact between the rod 610 and tube 620 and formation of a greencompact (“extruded material”).

In certain embodiments, the extrusion process may also include a channeldie 650 incorporated between the funnel 630 and the die 640. The channeldie comprises two wires 660 or the channel die may comprise other meansfor making internal channels in the green compact. The wires 660 areconnected to arms 670 which hold the wires 660 so they may contact theextruded material. The wires 660 result in the formation of channels inthe extruded material. The wires 660 may be made from any materialcapable of forming channels in the extruded material, such as, but notlimited to, nylon, polymer coated metal wire, polyethylene, high densitypolyethylene, polyester, polyvinyl chloride, polypropylene, an aramid,Kevlar, polyetheretherketone, natural materials, cotton, hemp, and jute.Preferably in certain applications, such as for formation of helicallyoriented channels, the wire is a flexible wire. However, for linearlyoriented channels and in some helical applications, rigid wires may beused. The channels may be used as coolant channels in rotary tools. Thewires 660 may be used to form helically oriented channels, linearlyoriented channels, or a combination thereof. A cross-section of the wireor other channel making component may be any shape, such as round,elliptical, triangular, square, and hexagonal.

Helically oriented channels may be formed in the extruded material inembodiments where the extruded material rotates relative to the channeldie 650. The extruded material may be rotated by incorporating spiralserrations in the die 640. In FIG. 6(c), extruded material 680 exits die645 that includes helical serrations on the internal surface of the die645. As the extruded material passes over the serrations, the extrudedmaterial is caused to rotate relative to the channel die (not shown).Alternatively, the die may rotate to cause the extruded material torotate relative to the channel die. Other channel dies may be used, suchdies comprising fixed helical coils wherein the extruded material iscause to rotate relative to the channel die in the same rotation as thehelical coils, or any other channel forming means.

The channel die may be a separate component or may be integral to thefunnel, die, or other component in the extrusion system. The channel diemay be capable of making at least one channel in the extruded material.The number and size of the channels may be limited by the size of theextruded material, the size of the channels, and the application for theultimate use of the extruded material. In embodiments comprising achannel die comprising wires, the number of wires will correspond to thenumber of channels formed in the extruded material. For an rotary toolapplication, it may be preferable to have an equal number of channels asthere will be flutes for example.

Embodiments of the present invention may further include loading thefeed chamber with at least two cemented carbide grades. At least onecemented carbide grade loaded in the feed chamber may be an extrudedform of either a rod, tube, bar, strips, rectangles, gear profiles, starshapes, or any other shape that may be formed in an extrusion process.In rotary tool or roller applications, it may be preferable that atleast one of the two cemented carbide grades be in the form of a rodshape and at least one cemented carbide in a shape of a tube. In otherapplications, the feed chamber may be filled with multiple tubes and/ormultiple rods of different cemented carbide grades. If multiple rods areused, the extruded material may be formed with specific grades ofcemented carbides in specific regions or randomly distributed throughoutthe cross-section of the extruded material.

A further embodiment of the present invention may comprise extruding acemented carbide grade to form an extruded green compact and pressingthe extruded green compact with a second cemented carbide grade to forma pressed green compact. The extruded green compact may optionallycomprise internal channels formed as described above, for example.

Actual examples of application of the foregoing method to providecomposite rotary tools according to the present invention follow.

Although the present invention has been described in connection withcertain embodiments, those of ordinary skill in the art will, uponconsidering the foregoing description, recognize that many modificationsand variations of the invention may be employed. All such variations andmodifications of the present invention are intended to be covered by theforegoing description and the following claims.

1. A composite article, comprising: at least a first region and a secondregion, wherein the first region comprises a first composite materialand less than 5 wt. % cubic carbides by weight, the second regioncomprises a second composite material, wherein the first compositematerial differs from the second composite material in at least onecharacteristic; and at least one coolant channel.
 2. The compositearticle of claim 1, wherein the first and second composite materialindividually comprise hard particles in a binder and the hard particlesindependently comprise at least one of a carbide, a nitride, a boride, asilicide, an oxide, and solid solutions thereof and the binder comprisesat least one metal selected from cobalt, nickel, iron and alloysthereof.
 3. The composite article of claim 1, wherein the characteristicis at least one characteristic selected from the group consisting ofmodulus of elasticity, hardness, wear resistance, fracture toughness,tensile strength, corrosion resistance, coefficient of thermalexpansion, and coefficient of thermal conductivity.
 4. The compositearticle of claim 1, wherein the first composite material and the secondcomposite material individually comprises a metal carbide in a binder.5. The composite article of claim 4, wherein the metal of the metalcarbide of the first composite material and the metal of the metalcarbide of second composite material are individually selected from thegroup consisting of group IVB, group VB and group VIB elements.
 6. Thecomposite article of claim 4, wherein the first region is autogenouslybonded to the second region by a matrix of the binders.
 7. The compositearticle of claim 4, wherein the binder of the first composite materialand the binder of the second composite material each individuallycomprise a metal selected from the group consisting of cobalt, cobaltalloy, nickel, nickel alloy, iron, and iron alloy.
 8. The compositearticle of claim 4, herein the binder of the first composite materialand the binder of the second composite material differ in chemicalcomposition.
 9. The composite article of claim 4, wherein the weightpercentage of the binder of the first composite material differs fromthe weight percentage of the binder of the second composite material.10. The composite article of claim 4, wherein the metal carbide of thefirst composite material differs from the metal carbide of the secondcomposite material in at least one of chemical composition and averagegrain size.
 11. The composite article of claim 4, wherein the firstcomposite material and the second composite material individuallycomprises 2 to 40 weight percent of the binder and 60 to 98 weightpercent of the metal carbide.
 12. The composite article of claim 11,wherein one of the first composite material and the second carbidematerial includes from 1 to 10 weight percent more of the binder thanthe other of the first composite material and the second compositematerial.
 13. The composite article of claim 1, wherein the compositearticle is one of rotary tool, a rotary tool blank, a drill, an endmill, a tap, a rod, and a bar.
 14. The composite article of claim 1,wherein the modulus of elasticity of the first composite material withinthe first region differs from the modulus of elasticity of the secondcomposite material within the second region.
 15. The composite articleof claim 1, wherein at least one of the hardness and wear resistance ofthe first composite material within the first region differs from thesecond composite material within the second region.
 16. The compositearticle of claim 1, further comprises two coolant channels.
 17. Thecomposite article of claim 1, wherein the at least one coolant channelis substantially straight.
 18. The composite article of claim 1, whereinthe at least one coolant channel is in a substantially helical shape.19. The composite article of claim 18, comprising two coolant channels.20. The composite article of claim 1, wherein the composite materialsare cemented carbides.
 21. A method of forming an article, comprising:coextruding at least two composite materials comprising metal carbidesto form a green compact.
 22. The method of forming an article of claim21, wherein the coextruding at least two composite materials isperformed through a die.
 23. The method of claim 22, wherein the diecomprises means for making internal channels in the green compact. 24.The method of claim 22, wherein the die comprises at least one wire. 25.The method of claim 24, wherein the at least one wire forms an internalchannel within the green compact.
 26. The method of claim 24, whereinthe die comprises at least two wire.
 27. The method of claim 26, whereinthe die comprises three wires.
 28. The method of claim 24, wherein atleast one wire is a flexible wire.
 29. The method of claim 28, whereinthe flexible wire comprises at least one of nylon, a polymer coatedmetal wire, polyethylene, high density polyethylene, polyester,polyvinyl chloride, polypropylene, an aramid, Kevlar,polyetheretherketone, cotton, animal gut, hemp and jute.
 30. The methodof claim 24, wherein the wire is an inflexible.
 31. The method of claim30, wherein the wire comprises a metal.
 32. The method of claim 21,further comprising: loading a feed chamber with at least two cementedcarbide grades.
 33. The method of claim 32, wherein at least onecemented carbide grade is in extruded form.
 34. The method of claim 33,wherein the extruded form is at least one of a rod, bar, and a tube. 35.The method of claim 32, wherein loading the feed chamber comprisesloading at least one cemented carbide grade in a rod shape and at leastone cemented carbide in a tube shape.
 36. The method of clam 33, whereina plurality of cemented carbide grades are loaded into the feed chamberin the shape of a tube.
 37. The method of claim 32, further comprising:extruding a first cemented carbide grade in the form of a tube.
 38. Themethod of claim 37, further comprising: extruding a second cementedcarbide in the form of a rod.
 39. The method of claim 38, wherein thecemented carbide in the form of a rod is extruded directly into a feedchamber of a coextruder.
 40. The method of claim 21, wherein compositematerials are cemented carbides.
 41. The method of claim 21, wherein thegreen compact comprises two cemented carbide grades and the cementedcarbide grades are coaxially disposed.
 42. The method of claim 21,wherein at the die includes a channel die.
 43. The method of claim 42,wherein the at least two cemented carbide grades are coextruded througha die comprising internal spiral serrations.
 44. The method of claim 42,wherein the at least two cemented carbides are coextruded through arotating die.
 45. The method of claim 22, wherein the green compactcomprises at least one channel.
 46. The method of claim 22, wherein thegreen compact comprises two helical channels.
 47. The composite articleof claim 1, wherein at least one of said first cemented carbide materialand said second cemented carbide material comprise tungsten carbideparticles having an average grain size of 0.3 to 10 μm.
 48. Thecomposite article of claim 1, wherein at least one of said firstcemented carbide material and said second cemented carbide materialcomprises tungsten carbide particles having an average grain size of 0.5to 10 μm and the other of said first cemented carbide material and saidsecond cemented carbide material comprises tungsten carbide particleshaving an average particle size of 0.3 to 1.5 μm.
 49. The compositearticle of claim 1, wherein the composite article is one of a drill, anend mill, and a tap.
 50. The composite article of claim 5, wherein oneof said first cemented carbide material and said second carbide materialincludes 1 to 10 weight percent more of said binder than the other ofsaid first cemented carbide material and said second cemented carbidematerial.
 51. The composite article of claim 1, wherein the modulus ofelasticity of said first cemented carbide material within said firstregion differs from the modulus of elasticity of said second cementedcarbide material within said second region.
 52. The composite article ofclaim 1, wherein the modulus of elasticity of said first cementedcarbide material within said first region is 90×10⁶ to 95×10⁶ psi andthe modulus of elasticity of said second cemented carbide materialwithin said second region is 69×10⁶ to 92×10⁶ psi.
 53. The compositearticle of claim 1, wherein the at least one of the hardness and wearresistance of said first cemented carbide material within said firstregion differs from the said second cemented carbide material withinsaid second region.
 54. The composite article of claim 1, wherein saidfirst cemented carbide material comprises 6 to 15 weight percent cobaltalloy and said second cemented carbide material comprises 10 to 15weight percent cobalt alloy.
 55. A method of producing a rotary toolhaving a composite structure, the method comprising: placing extrudedfirst powder metal into a first region of a void of a mold; placing asecond metallurgical powder metal into a second region of the void, theextruded first powder metal differing from the second metallurgicalpowder; compressing the mold to consolidate the extruded first powdermetal and the second powder metal to form a green compact; andover-pressure sintering the green compact.
 56. The method of claim 55,further comprising: removing material from the green compact to provideat least one cutting edge.
 57. The method of claim 56, wherein the moldis a dry-bag rubber mold, and further wherein compressing the moldcomprises isostatically compressing the dry-bag rubber mold to form thegreen compact.
 58. The method of claim 56, wherein removing materialfrom the green compact comprises machining the compact to form at leastone helically oriented flute defining at least one helically orientedcutting edge.
 59. The method of claim 55 wherein the extruded firstcompost powder comprises at least one channel.
 60. The method of claim59, wherein the extruded first powder metal comprises at least twochannels.
 61. The method of claim 55, wherein both the first powdermetal and the second powder metal comprise a powdered binder andparticles of at least one carbide of an element selected from the groupconsisting of group IVB, group VB and group VIB elements.
 62. The methodof claim 61, wherein the binders of the first powder metal and thesecond powder metal each individually comprise at least one metalselected from the group consisting of cobalt, cobalt alloy, nickel,nickel alloy, iron, and iron alloy.
 63. The method of claim 55, whereinthe first powder metal and the second powder metal each individuallycomprise 2 to 40 weight percent of the powdered binder and 60 to 98weight percent of the carbide particles.
 64. The method of claim 55,wherein at least one of the first powder metal and the second powdermetal comprises tungsten carbide particles having an average particlesize of 0.3 to 10 μm.
 65. The method of claim 55, wherein over pressuresintering the compact comprises heating the compact at a temperature of1350° C. to 1500° C. under a pressure of 300-2000 psi.
 66. The method ofclaim 55, wherein compressing the mold comprises isostaticallycompressing the mold at a pressure of 5,000 to 50,000 psi.
 67. Themethod of claim 55, wherein the green compact formed by compressing themold comprises: a first region comprising a first cemented carbidematerial provided by consolidation of the first metallurgical powder;and a second region comprising a second cemented carbide materialprovided by consolidation of the second metallurgical powder, the firstregion and second region differing with respect to at least onecharacteristic.
 68. The method of claim 67, wherein the characteristicis at least one selected from the group consisting of modulus ofelasticity, hardness, wear resistance, fracture toughness, tensilestrength, corrosion resistance, coefficient of thermal expansion, andcoefficient of thermal conductivity.